The invention relates to an electrical contact for use with a mating pin or blade contact to join electrical wires or other electrical conductors together.
It is well known in the art of electrical connectors to provide a receptacle contact or terminal for the receipt of a pin or blade contact where the receptacle contact has contact beams which extend from a receptacle body and are profiled to electrically engage a pin or blade contact upon insertion thereof. This contact between the receptacle contacts and its corresponding pin or blade contact interconnects the two pin and receptacle contacts and results in an electrical connection between the two and their associated mating conductors.
Multiple different requirements are involved in such an electrical device, particularly when used in a multi-position connector, for example when used in an automotive connector.
First, it is a requirement to provide a normal force between the receptacle contact and its associated pin or blade contact in order to provide the electrical connection between the two. In an effort to increase this normal force between the contact and the associated pin or blade contact, it is known to provide such devices as backup springs and other devices to enhance the normal force between the contact and its associated pin or blade contact. However in the instance of a multi-position connector, this enhanced normal force resultantly corresponds with an increased mating force as well which can negatively affect the overall objective. Suffice it to say that it is a delicate balance between the normal force of the mated connection, versus the mating force between the associated pin and receptacle contacts.
Other requirements that are necessary for multi-position connectors, is that the contact must be capable of sealing. In some cases, a discreet wire seal is crimped to individual contacts around individual wires, and the contact and its associated seal are inserted into an aperture in a connector housing. In other cases a rear seal is provided having a multitude of apertures through which individual contacts are inserted where the contacts are larger than the hole through which they extend, as the holes are nominally provided to sealingly engage the discreet wire to which they are connected.
One electrical receptacle is shown in U.S. Pat. No. 5,791,945 (incorporated herein by reference) where dual beam contacts are provided in a reversely bent sense such that their free ends overlap, with one beam forming a primary contact and the other beam providing a backup or secondary contact. In other words when a pin is inserted into the receptacle, the pin engages the primary contact and the insertion of the pin causes the deflection of the primary contact to a position where it engages the secondary and backup contact at which point the two travel together under an increased normal force.
While this concept is sound for some contact scenarios, as the contacts are reduced, some modifications are required. First, the contact has an anti-overstress feature which is stamped and struck from the top wall of the receptacle which extends downwardly to form an engagement lug with the secondary contact backup portion. Thus the primary and secondary contacts cannot be deflected beyond the position where the secondary contact engages its corresponding lug. As mentioned above, while this concept is sound for some contact sizes, as the contact is reduced in its overall dimensions, having the overstress feature extend from the top wall can cause an issue with dimensional stack up, as the receptacle “box” and the various metal thicknesses add to the dimensional disparity.
Also, the first and second contact arms, when used in a smaller dimension contact, can cause a “spiking” effect when the first and second contacts first engage each other. Said differently, due to the geometries of the primary and secondary contacts, when the primary contact makes engagement with the secondary contact, it engages along a line contact at the front edge of the secondary contact, the two then travel together until the two contacts are substantially parallel and overlapping, and then move to a position where the two are along a line contact engaging the rear edge of the primary contact. The point where the two contacts are in a flat position can cause a spiking of mating force due to the increased force required to overcome this flattened position.